Ball pen refill



- I Feb. 17,1970 1 R. L.SPAULDl-NG ,495,

BALL PEN REFILL Filed Jan. 15, 1968 INVENTOR. RA YMO/VD L. SPA ULD/NG Qzzu FE L 5.

United States Patent US. Cl. 401142 2 Claims ABSTRACT OF THE DISCLOSURE A ball pen ink cartridge includes a manually operable axially movable piston for applying pressure to force a compliant follower at the end of the ink column mto the constricted feed tube to enable write-out of substantlally all of the ink in the cartridge.

The present invention generally relates to ball pen writing instruments of the type which utilize a compllant follower at the rear end of the ink column, and it relates more particularly to new and improved means for enabling write-out of substantially all of the 1nk 111 the cartridge.

Compliant followers are usually composed of a greaselike substance which is immiscible with the ink and considerably more viscous, whereby such followers prevent the ink from leaking out of the rear end of the reservoir and they also seal the rear surface of the ink column from the atmosphere. The principal advantage of this type follower is that it permits the use of a relatively large diameter, high capacity reservoir. Such reservoirs ordinarily are connected to the point assembly by a relatively narrow, elongated feed tube through which the follower will not normally move under only the force of gravity and the pulling force, or negative pressure, applied to the follower by reason of the pull of the ball on the ink and the cohesive nature of the ink, upon application of the ink onto a writing surface from the rotating ball. Consequently, such pens will stop writing when the follower reaches the rear end or mouth of the feed tube even though a substantial amount of ink remains in the feed tube. It would be desirable, therefore, to provide means to enable this additional amount of ink to be written out and, moreover, to signal the user that the ink supply is nearly exhausted. In this way, the cartridge has, in a sense, a reserve supply of ink.

A principal object of this invention is, therefore, to provide a new and improved reservoir for a ball pen.

Another object of this invention is to provide a ball pen reservoir having a reserve ink supply.

A further object of the present invention is to provide a ball pen cartridge of the compliant follower type including means for exerting an auxiliary pressure on the follower to force it onto the feed tube after the follower has reached the mouth of such tube.

In the prior art there are disclosed various mechanisms for applying an auxiliary force to an ink column in the reservoir of a pen. Such mechanisms, however, operate continuously or intermittently during the write-out of the entire ink supply and do not, therefore, provide any warning to the user when the ink supply is nearly exhausted. Moreover, such mechanisms have not been employed for forcing a follower into the constricted feed tube of a ball pen cartridge.

Briefly, the above and further objects of the present invention are realized by providing a rear vented ink supply chamber connected to a ball point assembly by a narrow feed tube through which a viscous or compliant ink follower will not normally pass under only the force of gravity and ball pull on the ink upon a writing-out ice of ink onto a writing surface, and a manually operable means in the rear end of the chamber to increase the pressure on the follower and associated ink column when the follower reaches the mouth of the feed tube.

Further objects and advantages and a better understanding of the present invention may be had by reference to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a partially sectioned, fragmentary view of a ball pen cartridge embodying the present invention;

FIGURE 2 is a cross-sectional view of the device of FIG. 1 taken along the line 2-2 thereof;

FIGURE 3 is a cross-sectional view of the device of FIG. 1 taken along the line 3-3 thereof;

FIGURE 4 is a cross-sectional View of the device of FIG. 4 taken along the line 44 thereof.

Referring now to the drawings and particularly to FIG. 1 thereof, there is shown a ball pen cartridge 10 comprising a tubular shell 12 having a necked-down forward portion 14 which is connected to a ball pen assembly 16 by a relatively narrow elongated feed tube 18. The point assembly 16 may be conventional and includes a writing ball 20 rotatably mounted in a suitable socket which is supplied with ink through a longitudinal bore which opens at the rearward end of the assembly 16 into the feed tube 18. The ink supply 22 of the cartridge is thus contained in the point assembly, the feed tube 18, the neckeddown portion 14 and the main shell 12, and a compliant follower 24 which consists of a small quantity of grease or the like is provided at the rear end of the ink column. It will be understood by those skilled in the art that the follower 24 is immiscible with the ink 22 and is considerably more viscous than the ink. It is suffieiently fluid, however, to readily conform to the inner surface of the shell 12 as the ink is written out, and the follower is held by gravity and ball pull or atmospheric pressure against the rear surface of the ink column. However, the viscosity of the follower 24 is too great for it to follow the ink column into the necked-down area 14 and through the feed tube 18 by only the forces of gravity and the negative pressure or ball pull produced by the pumping action of the ball.

Means are provided to exert an auxiliary force on the follower 24 when it has moved as far forward as it can under these normally acting forces alone. Preferably, these means comprise a piston 26 mounted in the rear end ,of the shell 12 for axial movement into a constricted portion 28 having a cylindrical inner surface 30 which is slightly smaller in diameter than the external diameter of the piston 26. The shell is preferably formed of metal although plastic may also be used. Accordingly, when the piston 26 is moved into the constricted portion 28 the air located in the shell 12 between the follower 24 and the forward face of the piston 26 is compressed and exerts a forwardly directed force on the follower 24 and the ink column located forwardly thereof. This auxiliary pressure is sufficient to enable the follower 24 to thereafter move through the necked-down portion 14 and the feed tube 18 as the ink ahead of the follower is written out. This pressure is not so great, however, as to force the ball 20 out of its socket .or to squeeze the ink past it and out of the pen.

As shown in FIG. 1, the piston 26 has a threaded shank 32 which mates with internal threads in the bore 46 of a ratchet 34 rotatably mounted in the rear end of the shell 12. The ratchet 34 has an annular groove 36 into which the shell is deformed at 38 to rotatably secure the ratchet 34 in place. The rearward portion of the ratchet 34 inincludes camming and locking surfaces which are used in connection with the propel-repel mechanism of the pen holder with which the cartridge 10 is adapted to be used, but in the cartridge it also provides a convenient knob which the user may rotate with his fingers to move the piston 26 forwardly into its pressure applying position. A type of propel-repel mechanism suitable for use with the particular ratchet 34 shown in FIG. 1 is described and illustrated in United States Patent No. 3,205,863, issued on an invention ofNolan Kent Rhoades, but it will be understood that theparticula r shank of the ratchet 34 maybe modified to cooperate with other types of propel-repel mechanisms. The shank 32 of the piston is held against rotation my means of a collar 40 which is staked in place just forwardly of the ratchet 34. As best shown in FIG. 3, the collar 40 has a generally rectangular bore with flat sides 42 which are adapted to engage fiat sides 44 of the shank 32 to prevent rotation thereof. The collar 40 also has a radial slot 48 in its forward face to provide an air venting channel, as hereinafter explained. It will be seen that the shank 32 loosely extends through the collar 40 thereby.;to enable axial movement of the piston 26 relative to the collar 40 and also to pwvide an inner air passage thrpugh the; collar. As best shown in FIQ. 4, the fiat sides 44 of the piston shank 32 define air passageways through the centrally disposed annular bore 46 extending through the ratchet 34.

With the piston 26 in its retracted position, as shown in FIG. 1, an air passage from the upper surface of the follower 2 4 to thegatmosphere is thus provided around the piston 26, through the radial slot 48 in the forward face of the collar 40 and through the spaces between the shank 32 and the: walls of; the rectangular bore in the collar 40 and the wall .of the annular bore 46 in the ratchet 3.4.

In use, when the follower 24 reaches the necked-down portion 14 at the forward end of the cartridge, the writer will discover the pen has appeared to run out of ink inasmuch as the ball rotating in the socket is not capable of pulling the follower into the necked-down portion. When this occurs, he removes the cap from the pen and rotates the ratchet 34 a few turns to drive the piston 26 forwardly. Then pen will again write and the user is made aware that his ink supply is nearly exhausted. This operation may be repeated three or four times until the forward end of the follower 24 reaches the rear end .of the point assembly 16 or the piston 26 passes out of the forward end of the constricted portion 28, thereby relieving the pressure on the rear end of the follower 24. By this time, however, the user will usually have obtained a spare cartridge so that this cartridge which is now spent can be quickly replaced in the pen housing.

Since the cartridge is adapted to be held in a holder having a cap section threaded thereon, it is preferable that the threads on the piston shank be in a direction such that any tendency of the ratchet 34 to be rotated by the threading of the cap onto the barrel 12 will move the piston rearwardly of the cartridge. Hence, the threads are preferably selected to cause withdrawal of the piston when the ratchet is rotated clockwise.

While the present inventionhas been described} in connection with a particular embodiment thereof, it will be understood that those skilled in the art may make many changes and modifications without departing from the teachings of the present invention. Therefore, in the appended claims it is intended to cover all such changes and modifications as come within the true spirit and scope of this invention. e

I claim: e 1. A ball pen" ink cartridge including a point assembly, a rear-vented ink-containing reservoir, a compliant ink follower slidabie in said reservoir, and a constricted feed tube connecting said reservoir to the point assembly and being of a diameter through which said followeriwill not normally pass under only the force of gravity and the writing pull of the ball on the ink and follower, the improvement comprising a manually operable piston: mounted in said reservoir rearwardly of said follower and axially movable from a position where it does not close 011? the rear vent to the reservoir to a position in sealing relationship therewith, further movable into said cartridge while remaining in sealing relationship with said reservoir, and still further movable into said cartridge to a position where it again does not close off the rear vent to the reservoir, whereby when said follower reaches said feed tube said piston may be operated to apply and maintain pressure thereon to enable write-out of the ink in said feed tube, but the amount of pressure which can be applied by said piston is limited. 2. The invention according to claim 1 wherein said reservoir includes a rear portion having an internal diameter greater than the external diameter of said piston and a forward portion of slightly smaller internal diameter than the external diameter of said piston.

References Cited UNITED STATES PATENTS 3,075,497 1/1963 Tate 401187 3,113,558 12/1963 Marraffino 401-187 X 3,139,864 7/1964 Henriksen 401142 3,282,255 11/1966 Killen 401-187 3,334,616 8/1967 Urquhart 401-142 FOREIGN PATENTS 1,005,717 1/ 1952 France.

LAWRENCE CHARLES, Primary Examiner 

